Friday 18 January 2008 19.29 EST
First published on Friday 18 January 2008 19.29 EST

As one of the best and bravest of jump jockeys he risked life and limb taking part in - and winning - great races such as the Grand National and the Cheltenham Gold Cup.

But nine years after he retired through injury, Richard Dunwoody yesterday completed arguably his toughest task when he reached the South Pole via a previously unconquered route.

Speaking soon after completing his battle against altitude sickness and snow blindness in temperatures of up to -45C, Dunwoody told the Guardian: "This is the toughest thing I've ever done. When you're racing, you're a professional and it's your job.

"This was mentally and physically tougher with every day a 12 hour slog, often uphill, on skis and pulling cumbersome sledges that seemed to get heavier as we got lighter. I am exhausted. To arrive at the pole is my greatest achievement."

Dunwoody, who turned 44 yesterday, and an American explorer, Doug Stoup, took 48 days to cover the 680 mile route, only previously attempted by Ernest Shackleton almost a century ago.

Stoup was almost killed when he fell into a crevasse and a third team member abandoned the expedition half way through due to mental and physical exhaustion, leaving Dunwoody and Stoup behind time and having to walk 18 miles a day to get to the pole before bad weather closed in.

Both Stoup and Dunwoody lost more than 12kg (28lb), expending about 8,000 calories a day, but were only able to consume 5,500 in dehydrated and high-calorie foods. The loss took Dunwoody to around 63.5kg (10st) about his racing weight. "Tell Jonjo O'Neill [the racehorse trainer] that I'm ready for a ride," he joked.

The Dunwoody expedition followed the route Shackleton had planned to use for a trans-Antarctic expedition. But Shackleton's expedition failed when his ship, Endurance, became trapped in the ice.

Dunwoody, who prepared by running up to 60 miles a day and hauling tyres through Richmond Park, south-west London, got around this danger by getting to their starting point by plane.

The expedition immediately encountered a hugely challenging climb from sea level to 3,000 metres up the Slessor Glacier when the sledges were at their heaviest. The former jockey earned himself the nickname "10 Rhinos Dunwoody" for his strength in hauling the sledge.

Then came the Great Crevasse Field, where Stoup almost died, followed by a gruelling hike across the Polar Plateau. The routine was rigid. They woke at 6am and spent two hours melting ice for drinking water. The day was divided into up to eight sessions of 90 minute bouts of skiing - the "polar plod" as the great explorer Ranulph Fiennes calls it.

Each session was separated by a 5 or 10 minute food break but there was no lunch break because it would have taken too long to put the tent up. Finally they reached the Pole yesterday and celebrated with coffee, cookies and apple pie. "I feel knackered but elated," Dunwoody said.

Dunwoody was raising money for three charities - Sparks, which funds medical research for babies and children, Spinal Research and Racing Welfare.